Stabilized lithium metal impressions coated with alloy-forming elements and method for production thereof

Abstract

The invention relates to particulate lithium metal composite materials, stabilized by alloy-forming elements of the third and fourth primary group of the PSE and method for production thereof by reaction of lithium metal with film-forming element precursors of the general formulas (I) or (II): [AR.sup.1R.sup.2R.sup.3R.sup.4]Li.sub.x (I), or R.sup.1R.sup.2R.sup.3A-O-AR.sup.4R.sup.5R.sup.6 (II), wherein R.sup.1R.sup.2R.sup.3R.sup.4R.sup.5R.sup.6=alkyl (C.sub.1-C.sub.12), aryl, alkoxy, aryloxy-, or halogen (F, Cl, Br, I), independently of each other; or two groups R represent together a 1,2-diolate (1,2-ethandiolate, for example), a 1,2- or 1,3-dicarboxylate (oxalate or malonate, for example) or a 2-hydroxycarboxylate dianion (lactate or salicylate, for example); the groups R.sup.1 to R.sup.6 can comprise additional functional groups, such as alkoxy groups; A=boron, aluminum, gallium, indium, thallium, silicon, germanium, tin, lead; x=0 or 1 for B, Al, Ga, In, Tl; x=0 for Si, Ge, Sn, Pb; in the case that x=0 and A=B, Al, Ga, In, Tl, R.sup.4 is omitted, or with polymers comprising one or more of the elements B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, at temperatures between 50 and 300° C., preferably above the melting temperature of lithium of 180.5° C., in an organic, inert solvent.

Claims

1. A method for producing a stabilized particulate lithium metal, the method comprising: bringing lithium metal into contact with one or more passivating agents in a range of 180.5° C. to 300° C. in an inert organic solvent; wherein the one or more passivating agents is/are of formula I or formula II, where:
[AR.sup.1R.sup.2R.sup.3R.sup.4]Li.sub.x  (I)
R.sup.1R.sup.2R.sup.3A-O-AR.sup.4R.sup.5R.sup.6  (II) wherein each of R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 is independently of one another alkyl (C.sub.1-C.sub.12), aryl, alkoxy, aryloxy or halogen or two radicals R together denote a 1,2-diolate, a 1,2- or 1,3-dicarboxylate or a 2-hydroxycarboxylate dianion; radicals R.sup.1 to R.sup.6 may contain additional functional groups, A is selected from the group consisting of boron, aluminum, gallium, indium, thallium, silicon, germanium, tin and lead; x is 0 or 1 when A is boron, aluminum, gallium, indium, thallium; and x is 0 when A is silicon, germanium, tin or lead; wherein when x is 0 and A is boron, aluminum, gallium, indium or thallium, then R.sup.4 is omitted, and wherein the lithium metal has a content of sodium of less than 200 ppm.

2. The method according to claim 1, wherein two radicals R together denote 1,2-ethanediolate, oxalate, malonate, salicylate, glycolate or lactate.

3. The method according to claim 1, wherein the molar ratio between the lithium metal and the one or more passivating agents is 100:0.01 to 100:5.

4. The method according to claim 1, wherein the molar ratio between the lithium metal and the one or more passivating agents is 100:0.05 to 100:1.

5. The method according to claim 1, wherein inert organic solvent is selected from the group consisting of hexane, heptane, octane, decane, undecane, dodecane, toluene, ethylbenzene and cumene.

6. The method according to claim 1, wherein an additional coating step is performed by bringing the stabilized particulate lithium metal into contact with the one or more passivating agents at temperature of less than 180.5° C.

7. The method according to claim 1, wherein the stabilized particulate lithium metal has a core of metallic lithium which is surrounded with an outer passivating layer containing one or more elements of main groups 3 and/or 4 of the periodic table of elements that can be alloyed with lithium and wherein one or more elements of main groups 3 and/or 4 is/are present in the outer passivating layer in elemental form or as an alloy with lithium and the stabilized particulate lithium metal has an average particle size of max. 5000 μm.

8. The method according to claim 7, wherein the stabilized particulate lithium metal has an average particle size of max. 1000 μm.

9. The method according to claim 7, wherein the stabilized particulate lithium metal has an average particle size of max. 300 μm.

10. The method according to claim 7, wherein the lithium metal is spherical lithium metal selected from lithium powder or granules of ball shaped particles.

11. The method according to claim 1, wherein the lithium metal has a content of sodium in an amount of less than 200 ppm.

12. The method according to claim 1, wherein the lithium metal has a content of sodium in an amount of less than 100 ppm.

13. The method according to claim 1, wherein the lithium metal has a content of sodium in an amount of less than 50 ppm.

14. The method according to claim 1, wherein the one or more passivating agents are not gaseous, acidic, caustic, or toxic passivating agents.

Description

(1) FIG. 1 shows an x-ray diffractogram of the metal powder from example 1, passivated with a layer containing Si

(2) x: reflexes of lithium metal

(3) o: reflexes of Li.sub.21Si.sub.5

(4) FIG. 2 shows an x-ray diffractogram of the metal powder from Example 2 passivated with a layer containing Si

EXAMPLE 1

Production of a Lithium Metal Powder Having a Low Sodium Content, Passivated with a Layer Containing Silicon (Tetraethyl Silicate, TEOS, as the Passivating Agent

(5) 405 g Shellsol® D100 and 20.1 g lithium metal sections are placed in a dry 2-liter stainless steel double-jacketed reactor equipped with a dispersing agitator mechanism and inertized with argon. The lithium has a sodium content of 40 ppm. While agitating gently (approx. 50 rpm), the internal temperature is raised to 240° C. by jacket heating and a metal emulsion is produced by means of the disperser. Then 1.5 g TEOS dissolved in 10 mL Shellsol® D100 is added with a syringe within about 5 minutes. During this addition, the suspension is agitated with a strong shearing action. Then the agitator is stopped and the suspension is cooled to room temperature.

(6) The suspension is poured onto a glass suction filter. The filter residue is washed several times with hexane until free of oil and then vacuum dried.

(7) Yield: 19.2 g (95% of the theoretical);

(8) Average particle size: 140 μm (FBRM particle size analyzer from Mettler-Toledo);

(9) Metal content: 99.5% (gas volumetric);

(10) Stability in NMP, water content 167 ppm: stable for 15 hours at 80° C.; runaway reaction after 2.5 hours at 90° C.;

(11) Si content: 0.40 wt %;

(12) Surface analysis by XRD: phase components of Li.sub.21Si.sub.5

EXAMPLE 2

Production of a Lithium Metal Powder with a Low Sodium Content, Passivated with a Layer Containing Silicon (Vinyl Triethoxysilane as the Passivating Agent

(13) 415 g Shellsol® D100 and 98.4 g lithium metal sections are placed in a dry 2-liter stainless steel double-jacketed reactor equipped with a dispersing agitator mechanism and inertized with argon. The lithium has a sodium content of 40 ppm. While agitating gently (approx. 50 rpm), the internal temperature is raised to 240° C. by jacket heating and a metal emulsion is prepared by means of the disperser. Then 2.7 g vinyl triethoxysilane dissolved in 20 mL Shellsol® D100 is added with a syringe within about 5 minutes. During this addition, the suspension is agitated with a strong shearing action. Then the agitator is stopped and the suspension is cooled to room temperature.

(14) The suspension is poured onto a glass suction filter. The filter residue is washed several times with hexane until free of oil and then vacuum dried.

(15) Yield: 95.2 g (97% of the theoretical);

(16) Average particle size: 101 μm (FBRM particle size analyzer from Mettler-Toledo);

(17) Metal content: 99.7% (gas volumetric);

(18) Stability in NMP, water content 167 ppm: stable for 15 hours at 80° C.; a slightly exothermic reaction (no runaway phenomenon) after 2 hours at 90° C.;

(19) Si content: 0.26 wt %;

(20) Surface analysis by XRD: very little phase amounts of Li.sub.21Si.sub.5

EXAMPLE 3

Production of a Lithium Metal Powder with a Low Sodium Content, Passivated with a Layer Containing Silicon (Polydimethylsiloxane, PDMS as the Passivating Agent

(21) 405 g Shellsol® D100 and 20.6 g lithium metal sections are placed in a dry 2 liter stainless steel double-jacketed reactor equipped with a dispersing agitator mechanism and inertized with argon. The lithium has a sodium content of 40 ppm. While agitating gently (approx. 50 rpm), the internal temperature is raised to 240° C. by jacket heating and a metal emulsion is prepared by means of the disperser. Then 3.3 g polydimethylsiloxane (CAS no. 9016-00-6) is added with a syringe within about 3 minutes. During this addition, agitating is continued with a strong shearing action. Agitation is then continued for 30 minutes at about 210° C., the agitator is then stopped and the suspension is cooled to room temperature.

(22) The suspension is poured onto a glass suction filter. The filter residue is washed several times with hexane until free of oil and then vacuum dried.

(23) Yield: 20.1 g (98% of the theoretical);

(24) Average particle size: 51 μm (FBRM particle size analyzer from Mettler-Toledo);

(25) Metal content: 99% (gas volumetric);

(26) Stability in NMP, water content 167 ppm: stable for 15 hours at 80° C., then runaway after a few minutes at 100° C.;

(27) Si content: 0.70 wt %;

EXAMPLE 4

Production of a Lithium Metal Powder with a Low Sodium Content, Passivated with a Layer Containing Boron (Lithium Bis(Oxalate)Borate, LiBOB) as the Passivating Agent

(28) 396 g Shellsol® D100 and 19.1 g lithium metal sections are placed in a dry 2 liter stainless steel double-jacketed reactor equipped with a dispersing agitator mechanism and inertized with argon. The lithium has a sodium content of 40 ppm. While agitating gently (approx. 50 rpm), the internal temperature is raised to 210° C. by jacket heating and a metal emulsion is pre pared by means of a disperser. Then 6.1 g of a 30% solution of LiBOB in THF is added with a syringe within about 4 minutes. During this addition, the suspension is agitated with a strong shearing action. Next the agitator is stopped and the suspension is cooled to room temperature.

(29) The suspension is poured onto a glass suction filter. The filter residue is washed several times with hexane until free of oil and then vacuum dried.

(30) Yield: 20.5 g (107% of the theoretical);

(31) Average particle size: 43 μm (FBRM particle size analyzer from Mettler-Toledo);

(32) Metal content: 96% (gas volumetric);

(33) Stability in NMP, water content 167 ppm: stable for 15 hours at 80° C.; runaway after 4 hours at 100° C.;

EXAMPLE 5

Production of a Lithium Metal Powder with a Low Sodium Content, Passivated by a Layer Containing Boron (Triisopropyl Borate as the Passivating Agent

(34) 435 g Shellsol® D100 and 19.6 g lithium metal sections are placed in a dry 2 liter stainless steel double-jacketed reactor equipped with a dispersing agitator mechanism and inertized with argon. The lithium has a sodium content of 17 ppm. While agitating gently (approx. 50 rpm), the internal temperature is raised to 210° C. by jacket heating and a metal emulsion is pre pared by means of the disperser. Then 2.7 g triisopropyl borate dissolved in 20 mL Shellsol® D100 is added with a syringe within about 10 minutes. During this addition, the emulsion is agitated with a strong shearing action. Next the agitator is stopped and the suspension is cooled to room temperature.

(35) The suspension is poured onto a glass suction filter. The filter residue is washed several times with hexane until free of oil and then vacuum dried.

(36) Yield: 19.4 g (99% of the theoretical);

(37) Average particle size: 125 μm (FBRM particle size analyzer from Mettler-Toledo);

(38) Metal content: 97% (gas volumetric);

(39) Stability in NMP, water content 167 ppm: stable for 15 hours at 80° C.; stable for 15 hours at 100° C.; runaway after a few minutes at 120° C.;

(40) B content: 0.68 wt %;